Fluid-pressure-operated tool



E. H. SHAFF FLUID PRESSURE OPERATED TOOL Oct. 1151927.-

2 Sheets-Sheet l.

m. Q, .rw im @-llilllllww Oef. 11 192 .1 `A '1645166 7 -E.H.sHAFF FLUID PRESSURE OPRATED TOOL Filed May 1o, 1920 I z'ffsheets-sheet 2 m Imll..|

I a le Cil Patented Get. 11, 1927. l

UNITED STATES f 1,545,166 PATENT orrice.

ERNEST H. SHAFF, OF GRAN D HAVEN, lVICl-IIGAN, ASSIGTOR TO VJILLIAIYI I-I. KELLER, INC., F GRAND HAVEN, MICHIGAN, A CGREORATON 0F MCHIGAN.

FLUIDPRESSUREOPERATEB TOOL.

Application led May 10,

This invention relates to fluid-pressureactuated tools, and refers more particularly, though not essentially, to tools of. the percussion type commonly known as pneumatic hammers.

rIhe objects ofthe invent-ion are to produce a tool of novel and improved const-ruction in which a working charge of motive fiuid which moves the piston on its power stroke is separated into a primar7 and a secondary charge, the primary charge being utilized to continue the movement of the piston on its power stroke7 and the secondary charge being utilized to return the pis` ton; in which the entire control of motive fluid is effected by a single main control valve; and in which the efficiency of operation is greatly enhanced.

Further objects and advantages relating to details of construction will be pointed out in the following detailed description.

In the accompanying drawings Figure 1 is a longitudinal sectional view through a pneumatic hammer which is constructed in accordance with my invention. The sec tion is taken in the plane of line 1 1 of Fig. 3.

2 is an enlarged sectional view through the rear portion of the tool taken on the same plane as Fig. 1, but showing the main control valve in another position.

Fig. 3 is a transverse section in the plane of line 3 3 of Fig. 2.

Fig. et is a transverse section in the plane of line 4 4 of Fig. 1.

Fig. 5 is a longitudinal section through the tool taken in a plane indicated by line 5 5 of Fig. 3, which is substantially at right angles to the plane of Fig. 1.

Fig. 6 is an enlarged sectional View inthe same plane as Fig. 5 showing the rear portion of the tool with the valve'member in another position.

Figs. 7 and 8 are fragmental sectional detail views in the respective planes of lines 7 and 8 of' Fig. 3, showing certain chambers and passages in the valve mechanism.

My invention is herein shown as applied to a pneumatic hammer of the type illustrated, described and claimed in my cop-ending application Serial No. 371,445, filed April 5, 1920. It will be described in detail for the sake of clearness. but it should be understood that I do not intend to limit the invention to the present exemplary dis- 1920. Serial No. 380,017.

closure, but aim to cover in thev appended claims all modifications and equivalents falling within the scope of my invention.

The tool shown in the drawings comprises an integral body or cylinder 10 having an internal piston chamber in which a solid piston 11 reciprocates. In the forward end of the cylinder is fitted the usual rivet set or analogous working tool 12 against which the piston strikes at the end of its workin stroke.

At the rear end Vof the cylinder is the usual handle'13 having a tubular head 14 which may be mounted on the body in any preferred manner, as by means of screw threads, the handle being locked tothe cylinder to prevent rotation of the handle by any suitable means including a pin 15 and a sleeve or ring 15a. The handle has a supply passage 16 for live motive fluid, which passage is controlled by a manually operated throttle valve7 the lever of which is designated 17.

Fitting within afcounterbore at the rear end of the cylinder and partially enclosed by the head 14 of the handle is a tubular valve casing 18 which in the present instance is made of two interfitting sections. lWhen the handle is lturned up on its threads the valve casing sections are securely clamped inY place, and held against rotation by a dowel pin 18a.

A tubular valve member 19 fits slidably within the valve casing Y18 and'has a plurality of external annular flanges thereon forming shoulders or pressure areas against which the pressure of the motive fluid is exerted to move the valve member in 0pposite directions. Y Y

The handle head 111 provides an annular chamber 2O surrounding the rear end of the valve casing 18 and in constant communication with the supply passage 16 for the live motive fluid.

The rear end of the valve casing 18 is provided with inlet means 21, which may comprise an annular series of ports communicatingl with an internal annular groove in the valve casing, through which inlet means live motive fluid is introduced into the rear lend of the piston chamber to move the piston on its forward or power stroke v Alf V1n Fig.

sition by live air pressure in a small-valve chamber 22 actingl upon the small flange 23 on the valve'member, the said chamber being in constant communication.with the supply of live motivefluid through a small port 24a,

(Fig. 7 communicating with the chamber 22 by means of a by-pass '24 clearly shown 7. 1t will be obvious that at the beginning of the forward stroke the front end of the ley-pass 2li will be closed by the piston 11 and that after the piston 11 has passed the end of the bywpass it will also be in communication Vwith thelive motive fluid forcing the piston forward so that suitable pressure against flange 23 will be maintained.

During the forward stroke the dead air in front of the piston exhausts as best shown in Fig. 5 through one or more passages 25 communicating with an annular chamber 25 back of the large flange 26 on the valve 19, from which chamber a duct or ducts 27`lcad to the exhaust passages 28, which preferably open under a sleeve 15a' forming part of the locking means for the tubular head 14. Live motive fluid will thus be supplied toY force thepiston forward and theV dead air in front of the piston will be allowed to exhaust freely as long as the valve remains in the position illustrated infFigs. 1 and 5.

ln its travel'along the cylinder the piston .uncovers the end of a71: assage 29 (Figs. 1 and 2) communicating with the annular chamber 80 infront of the large flanger 26. The live motive fluid thereupon enters the passage 29V andiills the annular chamber as wellfas a plurality of storage, passages 31 Vof which l have illustrated three. storage passages communicate at their forward ends with the main cylinder, as shown, but said ends are vclosed by the piston before the rush of live motive fluid into them from the other end has discharged anyappreciable amount offair into the cylinder space in TDO Jllpiston. rlhe live motive, fluid Pressing against the front ofV the flange 2G overcomes the pressure onl the small'fiangev 23 and throwsthevalve back into the position illustra-ted in Figs. 2 and f3. During the first part of themovement of the valve the pressure on flange 26 will bejassisted by the pressure of the live motive fluid in the cylinder onfthe end .surface 32 of the valve member, which has an area greater than that of flange 23. Y

Y If desired, a small auxiliary port or feeder 33 may be located in about the position indicated in Fig; 1 to startthe 'discharge of live motive fluid into passage 20, `chamber 30 and passages 31 a trifle before the open `end.

of @passage-29 is uncoveredby the'piston. A moderate pressure may thus be' built up in the chamber 30 and passage 29 before the piston uncovers the endof the passage so that the action of the valve when the pas-V sage is uncovered will be more prompt.

These The movement of the valve to the position illustrated in Figs.2 and 5 cuts off the supply of live motive fluid from the annular chamber 2O to the cylinder and uncovers the annular chamber 84 which communicates directly with the exhaust passages 28. rl`he mainbody ofrair in the cylinder is then allowed to exhaust quickly and appro:-;imately at the same instant as the impact of the piston against the tool 12. The movement of the valve also operates to cover the ends of t-he ducts 27 with the edge of the large flange 26, enlarging the annular `chamber 3U 1n front of the flange and putting itin communicaticn with the passage 25 leading to the front. end of the cylinder, as clearly shown in F ig. 6. lThe contents of the annular chamber 25a pass out through duct 27 toi the exhaust passages 28, said annular chamber being completely closed by the movement ofthe valve.

Uponthe recoil ofthe piston 11 from the Y tool 12, the live motive fluid stored in the passages 31 at the time the valve 19 was shifted to the return stroke position will now flow through the annular chamber 30 'and the passage 25 to the front end of the cylk moves'to the rear and allows the storedV charge to expand. As soon `as the front ends of the storage passages 31 are uncovered on the return stroke, the stored air may enter the front part of the cylinder directlyV and substantial equilibrium of the pressure of the expanding charge in the various passages will be immediately attained. On yaccount of the rapid decrease in actuating pressure as the piston 11 moves hack, the velocityv it will attain at the end of the returnstroke will be very much less than that with which it struck the tool 12, thus diminishing the recoil at `the end of the return stroke.

During the major portion of the return stroke the by-pass 24: is in direct communication with Vthe rear part of the cylinder which is exhausted practically to atmospheric ,pressure by its direct communication with the exhaust passages 28. rlhe vsmall amount of live motive fluid entered through the port 24 is therefore inadequate to buildup any pressure behind thel flange 23. n s soon,

howeveigas the returning piston covers the trifle before the piston: 11 reaches the end of the return stroke so as to fill. the end of the cylinder back of the pistony with live motive fluid which receives and cushions the piston ll and immediately throws it back on the next forward stroke.

It will thus be apparent that the returning piston is received against a cushion otV air having'the full line pressure and that if its momentum is sufficient it may pump a small amount of air back into the line while coming to rest, whereas if it were cushioned on a completely enclosed body of air the pressure might rise much higher than the line pressure producing a much more severe shock as the piston stops. It should also be noted that if a defective valve should tend to stick in its rearwardposition shown in ig.v 6, the piston will then be cushioned on completely enclosed air trapped at approximately atmospheric pressurewhen the end of the piston passes the annular chamber 34. rlhis air upon being compressed by the piston will exert pressure on the end surface 35 of the valve and assist the pressure acting on the flange 23 inA shifting'the valve. In case of a serious defect resulting in complete jamming of the valve it should be noted that the piston will at allt events be received on an air cushion so that it cannot strike a blow against the head cast-ing, which would be likely to crack the same.

It will be seen that the tool I have provided contains no more parts than the tools of the prior art, but that I store part of the live motive Fluid used to force. the piston forward and deliver thesame 'in front of the piston on the return stroke to move the piston back, instead of wasting an additional amount of live motive fluid, which: would not only increase the consumption of live motive fluid but Aaccelerate the piston ll'towards the end of its return stroke to an entirely unnecessary and undesirable speed. Furthermore, the pressure in front of the piston All at the end of the return stroke may in a properly designed tool be practically atmospheric so that the difference in pressure on the ends of the piston as it starts forward will be the maximum obtainable. If live motive fluid .were used to return the piston, the passages for exhausting it could hardly be made adequate to bring the pressure in front of the piston to any such low value before the piston started backv on the next stroke.

I claim as my invention:

l. In a fluid-pressure-actuated tool, a

cylinder, a reciprocatory piston, a valveforv ed to liberate the stored charge during theM return stroke of the piston to actuate the piston on said; return stroke.

2.7111 a pressure-fluid-actuated tool, a cylinder, a reciprocatory piston, a control valve, a control passage uncovered by said pistonnear the end of the forward stroke to deliver pressure-fluid to shift said valve, storage passages receiving a charge of live motive fluid through said control passage at the time ofshifting of the valve, said storage passages being placed by said valve in communication with the front end of the cylinder whereby the stored charge acts to move the piston on the return stroke.

3.. In a fluid pressure actuated tool, a cylinder, a reciprocatory piston, a passage communicating with the -front endV of the cylinder, storage passages communicating with the cylinderadjacent the front end and aa cont-rol passage communicating with the cylinder at a` point uncovered by said piston near the front end of the stroke, a valve member adjacent the rear end of the cylinder having chambers in communication with all said passages and acting upon receipt of pressure fluid from said control passage to fill said storage passages with pressure fluid and then to connect them with the passage leading-'to the front end of the cylinder', at the same time disconnecting the rear portion of the cylinder from the source of pressure fluid and connecting it to the exhaust ports.

Il. In a fluidepressure-actuated tool, a cylinder, a reciprocatory piston in said cylinder, a control valve adjacent the rear end of said cylinder and a plurality of pasages controlled by said valve and coininunicating with said cylinderadjacent its front end, certain of said passages serving as exhaust means and other of said passages being controlled by said valve'whereloy to form storage means adapted to discharge into the front end of the cylinder to return the piston. I

5. In a fluid-pressnreactuatedr tool, a cylinder, a reciprocatoryv piston in said cylinder, an' annular control valve adjacent one end of said cylinder and adapted to con'- trol the flow of pressure fluid to and from the cylinder, a storage chamber having free communication with the cylinder adjacent the other end, and means carried by said annular valve for controlling the supply of fluid to said storage chamber. Y

6. In a fiuid-pressure-actuated tool, a cylinder, a reciprocatory piston in said cylinder, a main control valve adjacent one end of said cylinder and adapted to control the flow of pressure fluid to and from the cylinder, an exhaust passage communicating with the other end of the cylinder and a storage space independent of said exhaust passage controlled by saidvalve and also communicating with said' cylinder'adjacent its front eend. i

*7, In a luid-pressule-actuated tool, a

cylinder, a reciprocatory piston in said cylin- V8. In a. rluidpressureactuated tool, a

cylinder, a reciprocatory piston in said cylinder, an annular control valve at the rear end of said cylinder, exhaust and supply passages for the rear end of said cylinder controlled by said valve, an exhaust passage ttor the front end oiE said cylinder controlled by said valve and a storage chamber for trappingy a portion ot' live mot-ive fluid on the Y forward stroke `ot the piston and ldelivering it in `front of the piston on the return stroke, said storage chamber being controlled by said valve. Y n

9. In a pressuredluid-actuated tool, the combination of a cylin'derand a reciproca-V tory piston in said cylinjder, an annular con trol valve adjacent the rear end of said cylinder, exhaust ports arranged to Abe contrclled by thevextreme 'forward end ci said valve, inlet ports 4arranged to be controlled by the extreme rear-end of saidvalve, means providing a small annular pressure chamber for the valve, the .rear edge of said valve providing anarea exposed to the pressure developed in the rearend of the cylinder by the return ot the piston, and means including a passage opening into the cylinder near its-rear end soV as to be controlled by the piston in such return movement for eiiecting a building up of live pressurev in said pressure chamber, said passage being independent ot the valve and opening into the cylinder forwardly thereof.

l0. ln a luid-pressure-actuated tool, a cyl inder, an annular control valve adjacent one end of said cylinder, a Vflange on said control valve'defining annular chambers infront and behind said flange, four sets of passageways communicating with said chambers including an exhaust duct, a valvecontrol pas# sage, a storage passage, and a supply passage communicating with the extreme front end of the cylinder, said valve in one position j connecting said supply passagewith said er:-

haust'duct and said control passage with said storage passage and inthe other position connecting Vsaid storage passage with said supply passage and cutting o said control passage and said exhaust duct.

111. In a fluid-pressure-actuated tool, a one piece cylinder structure, a storage chamber in said cylinderl structure communicating with the cylinder adjacent its front end, and a control valve adjacent t-he rear end of the structure for lilling said storage chamber with live Huid on the :forward stroke 'and for connecting it to the extren'iefront end oli' the cylinder on th-e return stroke.

l2. In a fluid-jL fessure-actuated tool, a cyliuder, a storagechamber opening freely into said cylinder adjacent the front end, an annular chamber at the rear end of said cylinder communicating with said storage chamber, and Vvalve means in said annular chamber for automatically iilling said storage chamber during the forward stroke of said pistointhe front end of said storage chamber being covered by the piston while the` ch amber is being filled.

13. ln a fluid-pressure#actuated tool, a cylint er, a piston in said cylinder, a control passage uncovered rby said piston toward the end of .the forward stroke, a storage passage openingltreely into said cylinder, and means for filling said storage passage from said control passage while its front end is covered by the piston; Y

l la. In a pressure-iluid-actuated tool, the combination of acylinder, a piston, a valve having a small pressure chamber arranged so that in its rearmost position its're'ar end eX- tends"v into proximity tothe rear end of the cylinder but spaced therefrom, and means including a passage opening into the cylinder near its rear end so asto be controlled by the piston in its rearward movementv for confining live pressurenfluid insaid chamber whereby'to shift the valve member forward, said valve member providing in its rearmost position a closed pocket of substantial length in the rear endot the cylinder, said passage beingindependent ol? the valve and opening into the cylinder forwardly thereof.

l5. In a luid-pressure-actuate-d tool, a onepiece cylinder structure having passages formed therein of three different kinds including a -supply and exhaust passage communicating with the front end of the cylinder, a storage passage opening into the cylinder adjacent the frontend, and a control `passage opening into the cylinder at a point uncovered by the piston toward the end of the `forward stroke, both of the last mentioned passages extending to the rear end of the cylinder structure.

j 16. ln a fluid-pressureactuated tool, a onepiece. cylinder structure having passages `ornied therein oi' three different kinds including va supply and exhaustpassage comi 1icating with the stront end ot the cylj a storage passage,openinginto the cylinder adjacent thefront end, and a control vpassage opening into the cylinder at a point uncovered by the piston toward the end ofthe orward'stroke, both of the last mentioned. passages extending to the rear end of the cylinder structure, said storage passage being adapted to receive a charge of pressure fluid at its rear end from th-e rear end of said control passage and all of said passages opening directly and freely into said cylinder.

17. In a fluid-pressure-actuated tool, a one-piece cylinder structure having passages formed therein of three different kinds including a supply and exhaust passage communicating with the front end of the cylinder, a. storage passage opening into the cylinder adjacent the front end, and a control passage opening into the cylinder at a point uncovered bythe piston toward the end of the forward stroke, and a control valve operable upon delivery of pressure fluid to said control passage to fill the storage passage and then connect it to the supply passage.

i8. In a fluid-pressure-actuated tool, a cylinder, a piston in said cylinder, an imperforate annular valve adjacent the rear end of the cylinder, sait valve having flanges defining annular passages and operating to control the movement of the piston, the rearward movement of the valve operating to move the piston rearwardly, said rearward valve movement being limited by abutment of certain of said flanges with the cylinder leaving the rear edge of the flange eX- posed to the pressure in the rear end of the cylinder.

19. In a fluid-pressure-actuated tool, the combination of a main controlling valve and a storage chamber opening at its forward end into the cylinder and having at its rear end a Connection with the rear piston chamber controlled by said valve.

20. In a pressure-fluid-actuated tool, the combination of a'piston, and means for controlling the movements of the piston including a storage chamber opening at its forward end into the forward end of the cylinder and having at its rear end a valve-controlled communication with the cylinder substantially centrally thereof.

2l. A pressure-fluid-actuated tool having a piston chamber, a valve member operable to control the flow of pressure fluid to and from the piston chamber to effect the reciprocation of the piston, and a storage chamber adapted to receive under the control of said valve member a charge of pressure fluid from the rear piston chamber and to discharge such pressure fluid into the forward piston chamber.

22. In a pressure-fluid-actuated tool, the

combination of a piston chamber, valve means including a large pressure chamber and a small pressure chamber, a storage chamber opening at its forward end into the forward piston chamber and communieating at its rear end with the large pressure chamber, means controlled by the valve for admitting pressure fluid from the rear piston chamber to said large pressure chamber, and means controlled by the piston in its rearward movement for shifting the valve member forwardly.

23. A pressure-fluid-actuated tool having a piston chamber, an annular valve at the rear end of said chamber adapted to receive said piston, means controlled by the piston for exerting a gradually decreasing pressure upon the larger pressure area of the valve to hold it in its rearward position including a storage chamber, said valve member being adapted when in its rearward position to form a closed pocket for the receptionl of the piston and having its rearmost end eX- posed to the action of the pressure fluid compressed in said pocket by the piston.

24. A pressure-fluid-actuated tool having a piston chamber, a valve member forming in its rearward position a closed pocket adapted for the reception of the piston and having its rear end exposed to the action of the pressure fluid in the pocket, and means for exerting a gradually decreasing pressure upon the forward pressure area of the valve member as the vpiston approaches its rearward limit of movement, the last mentioned means comprising a passage opening at its forward end into the forward piston chamber and at its rear end opening into said pressure chamber.

25. A pressure-fluid-actuated tool having a piston chamber, valve means including-a valve member, a large pressure chamber and a small pressure chamber, a passage opening at its forward end into the forward piston chamber and at its rear end into the large pressure chamber, means controlled by said valve member for admitting pressure from the rear piston chamber to the large pressure chamber, and means controlled by the piston as it approaches the rear end of the cylinder for effecting a building up of live pressure fluid in the smaller pressure chamber.

In testimony whereof, I have hereunto set my hand.

ERNEST H. SI-IAFF.

CERTIFICATE OF CORRECTION.

Patent No. 1,645,166. Granted October 1l, 1927, to

ERNEST H. SHAFF.

It is hereby certified that error appears in the printed specification ot the above numbered patent requiring correction as follows: Page 4, after line 118, claim l5, after the word "structure" and before the period insert a comma and the words and a valve between the control passage and the storage passage operable to trap in the storage passage pressure fluid admitted to the control passage from the cylinder"; and that the :aid Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 1st day ef November, A. D. 1927.

M. J. Moore, Seal. Acting Commissioner ot Patents. 

